I integrated it with a RTC (DS1307) for the time. I don't have a GPS at the moment so I can't do it with that.
It's easy enough 
I'd love to use a compass and a GPS some time to make an automatic system that will track the sun anywhere without any values being programmed in.
Something I am going to using it for in the next month is for part of a lamp I am doing. Because I know when the sun has set, I can adjust lighting accordingly in the evening. Then there's no chance of sticking something on top of an LDR by accident and making the light turn on in the middle of the day when it's still light
Mowcius